1. Field of the Invention
This invention relates to an image recording apparatus, and more particularly to an image recording apparatus having a function of detecting a remaining amount of a photo-sensitive and pressure-sensitive sheet in the form of a roll.
2. Description of Related Art
Conventionally, in an image recording apparatus which uses a photo-sensitive and pressure-sensitive sheet in the form of a roll inserted in a cartridge for the exclusive use, a remaining amount of the sheet cannot be recognized from an external appearance. Thus, it has been a common practice that a last end of the sheet is detected by means of a contact type sensor or the like to indicate that the cartridge for the sheet has been empty. From such indication, a user perceives a timing at which the cartridge should be replaced by another new cartridge.
However, with such an image recording apparatus as described above, a user does not perceive the necessity of replacement of a cartridge until after the cartridge has been emptied. Therefore, an extra cartridge or the like must always be ready, which is inconvenient for a user.
Meanwhile, as a method of perceiving a remaining amount of the photo-sensitive and pressure-sensitive sheet in the form of a roll, a value of a number of images already produced subtracted from a producible number of images of the sheet in the form of a roll accommodated in a cartridge can be obtained readily.
However, the photo-sensitive and pressure-sensitive sheet in the form of a roll may not only advance but also retreat in an image forming cycle, and output images may have a plurality of sizes. In such a case, it is difficult to accurately indicate a remaining amount by counting a number of images produced.